1. Field of the Invention
The present invention relates to an information reproducing apparatus for reproducing recording information from a recording medium such as an optical disk on which the recording information having the hierarchical structure including a plurality of levels is recorded and, more particularly, to an information reproducing apparatus for reproducing recording information from a high-density optical disk such as a DVD on which the recording information having the hierarchical structure including a plurality of levels is recorded.
2. Description of the Related Art
A DVD is a high-density optical disk having a recording capacity about seven times as large as that of a conventional CD (compact disk). In recent years, a high-density optical disk typified by a DVD has been widely applied to not only the field of audio apparatuses or video players but also the field of so-called car navigation systems.
Recording information of a large capacity recorded on a high-density optical disk normally has the hierarchical structure composed of a plurality of levels (or plurality of classes) in order to achieve an efficient search operation. Different kinds of information units are assigned to the respective levels.
FIG. 1A illustrates recording information having the hierarchical structure of one level. In the case where the hierarchical structure is of one level, the recording information includes only a plurality of information units of the same kind, and therefore, its structure becomes simple. Each of the information units is referred to as xe2x80x9ca title.xe2x80x9d The recording information illustrated in FIG. 1A is composed of a plurality of titles 100A, 100B and 100C.
There are many cases where recording information having the hierarchical structure of one level is recorded on a DVD exclusive to a karaoke apparatus or sing-along machine, which is an apparatus or machine for playing karaoke music. The karaoke music is music which consists of accompaniments and back-chorus of songs.
The recording information recorded on the DVD exclusive to the karaoke music is composed of a plurality of karaoke songs and picture images respectively corresponding to the karaoke songs. In this case, one title is formed of one karaoke song and one set of picture images corresponding to the karaoke song.
FIG. 1B illustrates recording information having the hierarchical structure of two levels. In the case where the hierarchical structure is of two levels, the kind of information unit assigned to an high level is different from the kind of information unit assigned to a low level. The information unit assigned to the high level is referred to as a xe2x80x9ctitlexe2x80x9d; meanwhile, the information unit assigned to the low level is referred to as a xe2x80x9cchapterxe2x80x9d. In the recording information illustrated in FIG 1B, titles 101A and 101B are assigned to the high level; meanwhile, chapters 200A, 200B, 200C . . . and chapters 201A, 201B, 201C . . . are assigned to the low level.
Recently, there has been a DVD exclusive to karaoke music, on which the recording information having the hierarchical structure of two levels is recorded. In the case of such a DVD exclusive to karaoke music, one chapter is formed of one karaoke song and one set of picture images corresponding to the karaoke song. One title is formed of a group of the plurality of chapters.
By the way, when a DVD reproducing apparatus or a DVD player reproduces the recording information recorded on the DVD, a user operates ten-keys (numerical switches) disposed in the DVD reproducing apparatus to designate an information unit to be reproduced. Specifically, the user operates the ten-key to input a numeral indicating the information unit to be reproduced. As a result, the DVD reproducing apparatus searches the DVD for the information unit to be reproduced according to the input numeral.
Here, in the case where the hierarchical structure of the recording information recorded on the DVD is of two levels, it is necessary to decide whether the input numeral is a numeral for designating the information unit assigned to the high level or it is a numeral for designating the information unit assigned to the low level. For example, if the recording information illustrated in FIG. 1B is recorded on the DVD, it is necessary to decide whether the input numeral is a numeral for designating the title or it is a numeral for designating the chapter.
The DVD reproducing apparatus decides whether the input numeral is a numeral for designating the title or it is a numeral for designating the chapter based on whether the DVD is operative or inoperative. That is, a numeral input during inoperation of the DVD is decided to be a numeral for designating the title; meanwhile, the numeral during operation of the DVD is decided to be a numeral for designating the chapter.
Furthermore, another type of DVD reproducing apparatus is provided with a title search function and a chapter search function, and moreover, with a search mode selecting function of allowing a user to select either one of the two search functions. The title search function is a function of searching for a title; and the chapter search function is a function of searching for a chapter.
However, in the DVD reproducing apparatus having the search mode selecting function, there arises a problem that the user must perform a cumbersome operation in order to execute either the title search function or the chapter search function.
As to this problem, the DVD exclusive to the karaoke music is exemplified for the explanation.
As described above, in the DVD exclusive to the karaoke music, on which the recording information having the hierarchical structure of two levels is recorded, one karaoke song corresponds to one chapter. Consequently, when a karaoke song is selected from the DVD, the user must first select the chapter search function, and then, input a numeral indicating a desired song. If the user erroneously inputs a numeral in the state in which the title search function is selected, the DVD reproducing apparatus recognizes the input numeral as a numeral for designating a title. This results in reproduction of a karaoke song which the user does not intend to select (a karaoke song arranged at the head of the title). In this case, the user must select his or her intended song again.
On the other hand, in the DVD exclusive to the karaoke music, on which the recording information having the hierarchical structure of one level is recorded, one karaoke song corresponds to one title. Consequently, when a karaoke song is selected from the DVD, the user must first select the title search function, and then, input a numeral indicating a desired karaoke song. If the user erroneously inputs a numeral in the state in which the chapter search function is selected, the DVD reproducing apparatus recognizes the input numeral as a numeral for designating a chapter. Therefore, the DVD reproducing apparatus may determine the input numeral to be ineffective. Also in this case, the user must select his or her intended song again.
Additionally, the user need to select either one of the title search function and the chapter search function according to whether the hierarchical structure of the recording information recorded on the DVD to be reproduced is of one level or of two levels. This operation is cumbersome.
Moreover, in the DVD reproducing apparatus in which it is decided whether the input numeral is a numeral for designating the title or it is a numeral for designating the chapter, based on whether the DVD is operative or inoperative, there arise following problems: in this type of DVD reproducing apparatus, when the reproduction is started in the inoperative state, the input numeral is normally recognized as a numeral indicating the title. Consequently, a complicated operation is needed in order to select an arbitrary song in the DVD exclusive to the karaoke music on which the recording information having the hierarchical structure of two levels is recorded.
An object of the present invention is to provide an information reproducing apparatus in which an information unit in recording information recorded on a recording medium can be speedily searched with certainty even if recording mediums having different hierarchical structures are loaded.
An information reproducing apparatus in accordance with the present invention is an apparatus for identifying one of a plurality of information units recorded on a recording medium, and reproducing the identified one of the plurality of information units. On the recording medium, the plurality of information units are arranged in a hierarchical structure having a plurality of levels. The plurality of information units are divided into a plurality of groups. The plurality of groups are respectively assigned to the plurality of levels.
The information reproducing apparatus includes: an input device that receives an input instruction to designate one of the plurality of information units; a number determination device that determines the number of the information units included in each of the plurality of groups; a level determination device that determines, on the basis of a determination of the number determination device, one of the plurality of levels to be searched in order to identify one of the plurality of information units corresponding to the designated one of the plurality of information units; and a reproduction device that identifies one of the plurality of information units corresponding to the designated one of the plurality of information units by searching one of the plurality of levels determined by the level determination device, and reproduces the identified one of the plurality of information units.
In the information reproducing apparatus, the input device receives an input instruction to designate one of the information units. The number determination device determines the number of the information units included in each group. On the basis of the determination of the number determination device, the level determination device determines the level to be searched in order to identify the information units designated by the input instruction. The reproduction device identifies the designated information unit, by searching the level determined by the level determination device. If the designated information unit is identified, the reproduction device reproduces the identified information unit.
For example, if the number of the information units included in one of the groups (it is referred to as a xe2x80x9cgroup Axe2x80x9d) is greater than that of another one of the groups (it is referred to as a xe2x80x9cgroup Bxe2x80x9d), there is a greater possibility that the designated information unit is included in the group A. Therefore, in such a case, the level determination device selects the level to which the group A is assigned as the level to be searched in order to identify the designated information unit.
Thus, the designated information unit can be speedily and efficiently identified, if the information units are arranged in any hierarchical structure.
In the above-mentioned information reproducing apparatus in accordance with the present invention, it is assumed that (i) the plurality of information units are arranged in a hierarchical structure having a high level and a low level, (ii) the plurality of information units are divided into a first group and a plurality of second groups, (iii) the first group is assigned to the high level, and the plurality of second groups are assigned to the second level, (iv) the plurality of second groups are respectively dependent on some or all of the plurality of information units included in the first group. In this case, the number determination device may determine the number of the information units included in the first group and a maximum number of the information units included in each of the plurality of second groups. And, the level determination device may determine that one of the plurality of levels to be searched in order to identify one of the plurality of information units corresponding to the designated one of the plurality of information units is the high level, when the number of the information units included in the first group is not less than a first predetermined number.
When the number of the information units included in the first group is not less than the first predetermined number, it is determined that the number of the information units included in the first group is relatively large. Therefore, there is a great possibility that the designated information unit is included in the first group. In this case, the level determination device may select the high level as the level to be searched in order to identify the designated information, because the first group is assigned to the high level.
Further, the level determination device may determine that one of the plurality of levels to be searched in order to identify one of the plurality of information units corresponding to the designated one of the plurality of information units is the low level, when the number of the information units included in the first group is less than the first predetermined number and when the maximum number of the information units included in each of the plurality of second groups is not less than a second predetermined number.
When the number of the information units included in the first group is less than the first predetermined number and when the maximum number of the information units included in each second group is not less than the second predetermined number, it is determined that the number of the information units included in the first group is relatively small, but the number of the information units included in each second unit is relatively large. Therefore, there is a great possibility that the designated information unit is included in any one of the second groups. In this case, the level determination device may select the low level as the level to be searched in order to identify the designated information unit, because the second groups are assigned to the low level.
Further, the level determination device may determine that one of the plurality of levels to be searched in order to identify one of the plurality of information units corresponding to the designated one of the plurality of information units is the high level, when the number of the information units included in the first group is less than the first predetermined number and when the maximum number of the information units included in each of the plurality of second groups is less than the second predetermined number.
When the number of the information units included in the first group is less than the first predetermined number and when the maximum number of the information units included in each second group is less than the second predetermined number, it is determined that both of the number of the information units included in the first group and the number of the information units included in each second group are relatively small. In such a case, the level determination device may select the high level as the level to be searched in order to identify the designated information.
In the above-mentioned information reproducing apparatus in accordance with the present invention, the input device may receive the input instruction to designate one of the plurality of information units, in order to search the recording medium. Therefore, the search operation in the information reproducing apparatus can be speedily and efficiently carried out.
In the above-mentioned information reproducing apparatus in accordance with the present invention, the input device may receive the input instruction to designate one of the plurality of information units, in order to reserve a reproduction of the designated information unit. Therefore, the reservation for reproduction of information units can be speedily and efficiently carried out.
In the above-mentioned information reproducing apparatus in accordance with the present invention, the input device may have a plurality of numerical switches to designate one of the plurality of information units. Therefore, the information unit designated by the numerical switches can be speedily and efficiently identified.
In the above-mentioned information reproducing apparatus in accordance with the present invention, each of the plurality of information units may be a karaoke song data. Therefore, one of the karaoke songs can be speedily and efficiently identified.
In the above-mentioned information reproducing apparatus in accordance with the present invention, it is preferable that the first predetermined number is six, and it is preferable that the second predetermined number is six. In a recording medium exclusive to karaoke music, such as a DVD exclusive to karaoke music, the number of the information units recorded on one recording medium is six or more. Therefore, in the recording medium exclusive to karaoke music, if the number of the information units included in one group is equal to six or greater than six, there is a great possibility that the designated information unit is included in the group. Thus, in the case where a recording medium exclusive to karaoke music is reproduced by the information reproducing apparatus in accordance with the present invention, each of the predetermined first number and the predetermined second number is set to six. Accordingly, the processing of reproducing the karaoke music can be speedily and efficiently carried out.